pub fn escape_shell_arg(arg: &str) -> String {
    let mut output = String::new();

    for ch in arg.chars() {
        match ch {
            // Output a closing single quote, an escaped single quote, and then
            // resume the string by outputting a single quote.
            '\'' => output.extend(r"'\''".chars()),

            // Output a closing single quote, an escaped backslash, and then
            // resume the string literal by outputting a single quote.
            '\\' => output.extend(r"'\\'".chars()),

            // Other characters should be safe
            ch => output.push(ch),
        }
    }

    <[&str]>::join(&["'", &output, "'"], "")
}

#[cfg(test)]
mod test {
    use super::escape_shell_arg;

    // static INPUTS: &[&str] = [
    //     "hello, world",
    //     "i'm tricky",
    //     r#"this "one" is \"weird\""#,
    // ];

    #[test]
    fn hello_world() {
        assert_eq!("'hello, world'", escape_shell_arg("hello, world"));
    }

    #[test]
    fn escape_single_quote() {
        assert_eq!(r"'i'\''m tricky'", escape_shell_arg("i'm tricky"));
    }

    #[test]
    fn escape_backslash() {
        assert_eq!(r"'C:'\\'Windows'\\'System32'", escape_shell_arg(r"C:\Windows\System32"));
    }
}